Electrical control means



April 9 19449 A. o. GRQQMs ELECTRICAL CONTROL MEANS Filed Nov. 30, 1940 2 Sheets-Sheet 2 I INVENTOR. J1! M I fishnets 18, 1944 one!) STATES PATENT ovvicu ELECTRICAL CONTROL MEANS silica-t 0. Grooms, Dayton, Ohio, assigncr to Genemi Motors il'orporation. Dayton, Ohio, a corporation of Delaware Application November 30, 1840, Serial No. 367,991

3 Ciaims. (Cl. 172-279) This in ention relates to electric controls and motor control means.

Various schemes have been used for controlling electric motors. in the most of these schemes mechanically operated contact mechanisms are used. Such contacts are subject to deterioration.

it is an object of my invention provide a starting control for on electric motor which has no mechanical moving parts.

it is another object of my invention to provide an overload control for an electric motor without mechanical moving parts.

It is another object of my invention to provide a temperature control without mechanical moving parts.

It is another object o! my invention to provide a trouble-free starting control which will operate uniformly over a great period of fime.

It is another object of my invention to provide a trouble-free temperature control which will operate uniformly over a long period of time.

It is another object of my invention to provide a regulating means for controlling the operation of a sealed-tube type of control.

Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accom-paving drawings, whereina preferred form of the present invention is clearly shown.

In the drawings:

Fig. l is a view, partly stic, of one form of my invention applied to an electri motor driving a refrigerating system;

Fig. 2 is a fragmentary view showing a modiilcation of a portion of Fig. 1;

Flg.3isaview simiiartoFig.1showingthe invention applied to a capacitor motor and showing one term of the invention used for controlling the motor and the refrigerating system according to the temperature of a refrigerated compartment: and mg. 4 is a fragmentary view showing another scheme for varying the starting and stopping temperatures.

Briefly, I provide a trouble-free motor control byemployinsasealedtubeofglassorothersuitable material having at least one electrode in each endandareducedneckportionor asmallcalibrated cross-sectional area connecting the tube portions provided with electrodes. The tube is filled with a liquid capable of serving as a conductor, which liquid will evaporate when a sum- .cimt heat is generated either by the current plied to the neck portion The generation of heat at that point will cause the liquid to evaporate and separate at the neck to stop the new 0! electric energy between the electmdee upon opposite sldes of the neck. If desired, a. third electrode may he provided which will he contacted when the liquid level is raised by the evaporation of some of the liquid at the neck portion.

Referring to the drawings and more particularlv to Fig. i, there is shown an electric motor. generally designated by the reference character 2!, which is adapted to be housed in a sealed unit 22 of a compression reirlgerating system. This sealed unit 22 also contains a compressor directly driven by the motor I! for forwarding compressed reirigerant to ncondenser 21 where the compressed refrigerant is liquefied and conducted to the evaporator 2i underthe control of a suitable valve 28. The refrigerant evaporates under reduced pressure within the evaporator 26 to cool the compartment SI and the evaporated refrigerant is returned to the compressor through the return conduit.

The motor 2! is of the split phase type includingamainwindingfiandaphaseorstartlng winding". whllethemotorzllsshownasa part of the retrlzeratlng ystem it should be understood thatitmaybeusedioranqpurpose. The starting and stopping of the motor it is controlled by a thermostat switch 38 which connects the common junction 38 oi. the main and phase windlngsflanduwithoneconductorlioi'the supply source. The other conductor 42 or the supply source is provided with a conductor connectlngto anelectrodeflinoneendotaaealedtuhe 4 formed of glass or other suitable material. Attheoppositeendotthembelltherelspm videdaaecondelectrodellwhlchis connected hyaconductoril totheotherendotthemain winding 8!.

thisnockporflonisrcdnoedto eenthetwoelectmdesilandlt. Preierablv' heat thereto for keeping the electrodes 52 and I8 separated electrically after the starting period. The tube 56, like the tube 86, preferably contains a somewhat volatile liquid M which is capable of carrying an electric current without difficulty. For example, mercury may be used or water which is ionized by the addition of a suitable ionizing substance such as a small amount oi! sodium or other salt or acid. The tube may either be evacuated or it may contain a non-oxidizing gas,

such as nitrogen or hydrogen. At opposite ends of the tube above the liquid level there are provided pockets 5d and 68 for receiving the liquid displaced when a portion of .the liquid evaporates in the neck portion 58. However, only one pocket is required. The liquid in the portion 58 may evaporate due to the heating efiect of the current flowing from the electrode 52 to the electrode 58 through the small passage in the neck 58, or by the heat produced by the heater St, or both. The bore of the neck of the tube, the liquid used and the amount of heat generated should be such that the liquid is evaporated at the neck 58 in order to open the circuit of the phase winding 38 when the motor reaches approximately full speed. The bore of the neck of the tube is the primary factor in controlling evaporation at that point while the Y heater portion 60 serves mainly to keep the liquid in order to separate the liquid in the ends of the tube to stop the-now of current. This tube may likewise be either evacuated or charged with a non-oxidizing gas such as nitrogen or hydrogen.

In Fig. 2 a slightly modified arrangement for the overload control tube is shown. In this arrangement, the source conductor M2 is first wrapped around the neck ltd of the tube its after which it connects to the electrode M6 at the one end of the tube. At the other end of the tube there is provided an electrode M8 which is connected by a conductor ltd to the main ascaess extends to the common junctionttt between the main winding 232 and the phase winding 234 of a capacitor type motor 220.

The sealed tube 254 diflers' somewhat from the sealed tube 54 of Fig. 1 in that it is provided with 1 a third electrode 280 located in the displacement space 288 at one'end of the tube'above the normal liquid level therein. No displacement space is provided at the opposite end of the tube where w the first electrode 252 is located below the liquid level. At the opposite end of the tube, the second electrode 258 is located below the liquid level. The tube 254 contains a liquid capable of carrying electric current sufliciently volatile to evapo- 282 with a capacitance means 2815 having a cawinding of the split phase motor. This conduc- I In Fig. 3 are shown two further developmentsof my tube-type control applied to a capacitor motor for driving a refrigerating system. In this figure, one source nductor 242 has a rotatable contact member 2 3 connecting to various taps 265 extending from points on the heating portion 267 wrapped around the neck 26d of a sealed glass tube 246, having an electrode 254, at one end connected to the heating portion 26!. .At the other end, there is provided an electrode 243 connected to a conductor 25!! having a heating portion 280 wrapped around the neck portion 253 pacitance selected for starting purposes. This capacitance means 285 is connected to one end of the phase winding 2%. The electrode 28b is connected to the capacitance means 2% which has a capacitance selected for normal running of the motor. 252 and 280 may connect to suitable taps upon a transformer employed to vary the capacitive reactance of the capacitance means connected to the phase winding 23%. The electrode 256 as well as the other end of the main winding 232 are connected to the source conductor 2%.

The tube 266 is located within the compartment 298 which is cooled by an evaporating means tti of a refrigerating system which includes a sealed unit compressor 3% which withdraws evaporated refrigerant from the evaporator so: and forwards the compressed refrigerant to a condenser 305 from which liquid refrigerant returns to the evaporating means 3M under the control of a suitable flow control device 38?. The capacitor motor 226 is preferably located in the sealed unit 308 and -connected directly to the compressor therein. Since the air within the compartment 298 circulates, the tube 2% not only will be responsive to the temperature of the air therein but will likewise be responsive to the temperature of the evaporator til i.

In addition to the electrical conducting liquid. the tube 245 preferably contains a small amount of a second volatile liquid which will evaporate at a lower temperature and preferably will evaporate substantially at the temperature atwhich it is desired to maintain the air in the compartment 29d. For example, tetrafiuorodichloro ethane (F-lld) having a'boiling point of 39 F. may be used if desired This second volatile liq= uldwill make it possible for the tube 2416 to 019- gralte as a thermostat as-well as an overload con- When the temperature within the compartment 298 is above normal, the second volatile liquid will create suflicient pressure within the tube 24% to condense all 0! the conducting liquid to close the motor circuit and start the operation of the refrigerating system. As the compartment 298 of a sealed glass tube 234. This conductor 25!! 7g cools, the pressure of the second volatile liquid If desired, however, the electrodes will be reduced, allowing the electrical conducting liquid to evaporate in the neck portion 266 of the tube 246 when the compartment 298 reaches a predetermined low temperature.

Should there be an excessive amount of current flowing through the heater portion 261 and the tube 246, the heat generated thereby will be suflicient to evaporate the conducting fluid at the neck portion 268 to break the circuit between the electrodes 24! and 248 regardless of the temperature and pressure of the second volatile liquid in the tube 246.

The rotatable contact member 243 may be moved from any one of the taps-265 to any other in order to vary the eflective length of the heating portion 261. This will vary the amount of heat generated by the heating portion 261 and thereby will vary or change the temperature at which the liquid in the tube 246 is joined and separated to close and open the motor circuit.

When the motor starts the current will flow through the conductor 252, the rotatable contact member 253, one of the taps 265, the heating portion 26?, electrode 245, the sealed glass tube 246, the electrode 246, the conductor 250 and q the heater 260 to the common junction 238.

Current will also flow from the source conductor 24' to the main winding 232 as well as to the electrode 256. From the electrode 256 current will flow through the tube 254 to the electrode 252 and through the conductor 282 to the capacitance means 284 for energizing the phase winding 234 for starting purposes. Heat will normally be generated at the neck 258 by the heater 260 as well as the current flowing through the tube 25d and when the motor approaches running speed the liquid will evaporate in the neck 258 to separate electrode 252 from the electrode 256 and cause the electrode 280 to he contacted by the electrolyte. This will break; the current to the capacitance means 284 and cause the current to low from the electrode 280 to the capacitance means 286 and the phase winding 224 for the running period. If desired this tube 252 may be used to vary the capacitance applied by other means such as a transformer.

The motor will be stopped when the tube 246 is cooled sufliciently by the air in the compartment 298 to enable the heat generated at the neck portion 266 to cause evap'orationat that portion to break the circuit between the electrodes 244 and 248 to stop the motor.

In Fig. 4, there is shown another scheme for controlling the heat applied to the neck of the tube 246. In this scheme a variable or adjustable resistance 296 is connected in series with the heating portion 26! across the supply conductors 240 and 242. The adjustment of the variable resistance 296 will change the amount of heat generated at the neck portion ofithe tube 246 and thus will change the temperature at which the liquid is joined arid separated in the tube 266.

While theform oi embodiment of the invention as herein disclosed,iconstitutes a preferred form it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

What is claimed is as iollows:

1. In combination, an electric motor having main and phase windings, a control for changing the energization of the phase winding comprising a sealed container of electrical insulating material, said container having a capillary portion providing a connecting iluid passage of small cross-sectional area between the other portions of the container, said container being provided with an electrode upon either side oi the capillary portion, one of said electrodes being connected to one end of the phase winding and the other to a source of electrical energy, means connecting the other end of the phase winding and both ends of the main winding to said source, said container containing an'electrical conducting liquid sufllciently volatile to form a vapor barrier when heat is applied at the neck portion, and means for preventing the breaking of the vapor barrier during the remainder of each operating period of the motor following the change in the energlzation oi the phase winding including means for heating said capillary portion coincidentally with the energization of the main winding.

2. In combination, an electric current control including a sealed container containing an electrical conducting liquid, said container having a vapor retaining connecting portion of electrical insulating material providing a connecting fluid passage of small cross-sectional area, said container being provided with an electrode upon each side of the connecting portion, said electrodes being connected to conductors, said conducting liquid being sumciently volatile to evaporate and separate electrically said electrodes when sufficient heat is generated at said connecting portion, said sealed container containing a second volatile liquid for creating a vapor pres sure afiected by environment temperature for varying the current breaking point.

3. In combination, a capacitor type electric motor having main and phase windings and capacitance means, a control for controlling the connection of said capacitance means to the phase winding. comprising a sealed container containing an electrical conducting liquid, said sealed container having a capillary portion providing a connecting fluid passage oi small crosssectional area, said sealed container having a space on one side of the capillary portion above the normal liquid level and a first electrode in .said space so located that it will be contacted by the liquid when the liquid is forced out of the connecting fluid passage, said container also having second and third electrodes located below the liquid level on opposite sides of said capillary portion, the walls of said container including insulating means for insulating said electrodes from each other and from said capillary portion, means connecting said first and one of the second and third electrodes to said capacitance means for changing the connection of the capacitance means to the phase winding for changing the effective value of capacitance applied to the phase winding, means connecting the other electrode and the windings to the source of energy, the last named means including connections from the capacitance means to the phase winding and from the latter to the source of energy, and means for heating the capillary portion coincidentally with the energization of the main wind- 4. In combination, an electric current control including a sealed container containing an electrical conducting liquid, said container having a vapor retaining connecting portion between two reservoir portions of the container providing a connecting fluid passage of small cross-sectional area, said electrical conducting liquidextending through said connecting portion to said two reservoir portions partially filling one of said res ervoir portions to a certain level, said one reservoir portion being provided with one electrode extending below the liquid level and a second electrode located entirely a small distance above the normal liquid level, said container belng'provided with a third electrode on the opposite side of the connecting portion extending below the liquid level of the reservoir portion, said con-= tainer being provided with means for insulating the electrodes from each other and from the connecting portion, said conducting liquid being suiiiciently volatile to evaporate and separate electrically at the connecting portion and to contact said second electrode when suflicient heat is generated at the connecting portion.

5. In combination, an electric motor ha main and phase windings, a plurality of capacitance means, means for connecting one terminal of each capacitance means together and with the phase winding, a control for changing the energization of said capacitance means comprising a sealed container containing an electrical conducting liquid, said sealed container having a connecting portion providing a connecting fluid passage of small cross-sectional area, said sealed container having a space on one side oi the 'connecting portionabove the normal liquid level and having a first electrode in said space so located that it will be contacted by the liquid when the liquid is forced out of said connecting fluid passage, said container also having second and third electrodes located below the liquid level on opposite sides of said connecting portion, the walls of said container including insulating means for q insulating said electrodes from each other and from the middle of said connecting portion, means connecting said first electrode with the other terminal of one of said capacitance means, means connecting the electrode located below the liquid level upon the opposite side of the connecting portion from said space with the other terminal of another of the capacitance means, means connecting one side of the power source .with an electrode located below the liquid level on the same side of said connecting portion as said first electrode and one end of the main winding, means connecting the common junction between the main and phase, windings with the other side of the power source, and means for heating the connecting portion "coincidentally with the energization of the main winding.

6. In combination, an electric motor having main and phase windings, means for energizing said windings including a power source connected to the windings and control means connected between the power source and the phase winding for changing the energization of said phase win ing at the end oi the s 1 1 ing liquid, said container having a liquid separating vapor retaining portion located at least in part below the normal liquid level of the conducting liquid for separating the liquid upon the accumulation of sumcient vapor and a set of electrodes insulated from one ano er projecting into said volatileliquid on opposite sides of said vapor retaining portion, one of said electrodes being connected to the power source and the other to the phase winding, said control means including means for supplying heat to the portion of said liquid adjacent the vapor retaining por-- tion during the starting period of the motor so as to form a vapor barrier in said vapor retaining portion at the end of the starting period to change the energization of the phase winding and for supplying heat during the remainder of the operating period of the motor to maintain said vapor barrier to keep changed the energizetion of the phase winding.

7. In combination, a capacitor type motor having main and phase windings and capacitor means connected to the phasewinding, said capacitor means having a plurality of connec-.

tions providing diiierent values of capacitance, means for energizing said main and phase windings and said capacitor means comprising a powersource connected to said windings and a control means connected to said powersource and'capacitor means for changing the energization of the capacitor means and the phase winding including a sealed container containing a I volatile electrical conducting liquid, said container having a liquid separating. vapor retaining portion located at least in part below the normal liquid level of the conducting liquid for separating the liquid upon the accumulation oi sumcient vapor and a set of electrodes insulated from one another projecting into said volatile liquid on opposite sides of said vaporretaining portion, one of .said electrodes being connected to the powersource and'theotli'r to one or the connections of the capacitor means said container having another electrode connected to another connection of the capacitor means to provide a changed energization of the capacitor means and located above the normal liquid level at a point so as to be contacted by a rise in liquid level resulting from the formation of a vapor barrier in the vapor retaining portion, said control means including means for supplying heat to the por tion of-.said liquid adjacent the vapor retaining portion during the starting period of the motor to form a vapor barrier in said vapor retaining portion at the end'of the starting period and for supplying heat during the remainder of the operating period of the motor to maintain said vapor barrier to keep changed the energization of the phase winding.

8. In combination, an electric current control including a sealed container containing an elec-. trical conducting liquid, means for heating said liquid to change the ratio between the liquid and gas phases thereof, a set of electrodes in said container located so as to be bridged and unbridged by the liquid according to the che in ratio of said liquid and gas phases, said sealed container containing a second volatile liquid for creating a vapor pressure affected by environment temperature for varying the current breaking point.

' ERT O. GROOMS. 

